1. Field of the Invention
This invention relates to a current collection apparatus and its method of processing for a solid oxide fuel cell, it specifically relates to a current collection apparatus and its processing method so that a direct connection can be made with the electrode to reduce the entire interface impedance and to enhance the electrical conductivity efficiency.
2. Description of the Prior Art
Today, the petroleum storage on earth is reduced gradually, along with the gradual attention of environmental protection and green house effect gas CO2 topic, the development of more environmental protection energy storage and energy conversion technique thus becomes so important. Solid oxide fuel cell (SOFC) has high performance energy conversion efficiency, it is of no noise, of low environmental pollution, of high reliability, meanwhile, the fuel is diversified and the power can be generated continuously and stably, hence, it is a power generation apparatus that has the greatest potential.
Since all the components of a general solid oxide fuel cell are solids, hence, the cell design is diversified, currently, the commonly used design can be divided into tubular type and planar type, among them, the planar structure has lower manufacturing cost, simple process and easier-to-develop thin film electrolyte, hence, planar structure is more widely studied. In recent years, in order to enhance the power density of the solid oxide fuel cell, the goal is usually put on the reduction of the polarization loss and ohmic loss of the cell. Polarization loss is usually surmounted through new material development and the improvement of electrode structure, for example, due to the insufficient high temperature ionic electrical conductivity, LSM cathode is gradually replaced by LSCF, meanwhile, pore former is added in the electrode to enhance the diffusion rate of gas in the electrode; moreover, the reduction of the entire ohmic loss is improved through the improvement of thin film technology so as to reduce the electrolyte thickness. However, generally, the entire ohmic loss not only is related to the electrolyte thickness, but also is highly related to the contact resistance between electrode and current collection apparatus, and contact resistance is always seen as the key factor affecting the power density of the cell.
As shown in FIG. 1, it is the structure of typical and traditional current collection apparatus, and it has a current collection apparatus 6 that is in direct contact with the surface of the electrode 4 of the solid oxide fuel cell. In the actual application, in order to reduce the contact resistance between the current collection apparatus 6 and electrode 4, the cell piece, the most commonly seen method is to increase directly the contact pressure between current collection apparatus 6 and electrode 4 so that close contact can be formed between both of them, and contact resistance can then be effectively reduced, however, too much pressure might usually lead to the difficulty in cell piece to take the external pressure and the final breakage, hence, the entire cell stack must be replaced due to the damage of only few cell pieces.
Due to the above drawbacks of the prior art current collection apparatus and processing method of solid oxide fuel cell, the inventor has thus provided much of improvements as described in this invention.